The present invention relates generally to jet pipe burners for use in an industrial furnace and more particularly to a seal for sealing the interior of the jet pipe containing the burner from the interior of the furnace. The seal is arranged between an end face of the jet pipe and a burner flange containing a recess for receiving that end of the jet pipe.
Typically, seals of this type have been made of silicone and, accordingly, are susceptible to natural wear. Such seals have a relatively short service life. If a silicone ring or seal is damaged, leaks will occur and the protective gas within the furnace will flow into the jet pipe where it will burn with a very intense flame. Consequently, this will lead to significant damage to the heating system. There is also a possibility that heating gas will flow from within the jet pipe into the interior of the furnace and will adversely affect the atmosphere within the furnace by increasing its CO.sub.2 content. This will result because either the carburization time is increased or, if this time remains constant, the marginal carburization will be reduced. During the carburization process, the furnace atmosphere contains approximately 0.05% to 0.15% of CO.sub.2, while the fuel gas in the jet pipe contains from 10 to 12% CO.sub.2. The seal is replaced, however, only after the furnace atmosphere is highly contaminated and, as a result, there is an increased loss of protective gas and a longer carburization period. Additionally, protective gas in the jet pipe causes false flame formation which results in increased damage to the jet pipes and burners. Replacement of a damaged seal requires shutdown of the furnace which tends to be very costly.
Accordingly, the primary object of the present invention is to provide a seal which, while furnace temperatures increase, affords a hermetic sealing action between the interior of the jet pipe in an industrial furnace and the interior of the furnace so that the necessary carbon potential in the furnace can be rapidly reached, and the maintenance costs for the industrial furnace can be reduced.